The invention is based on a fuel injection valve for internal combustion engines as set forth hereinafter.
In the case of a well-known fuel injection valve of this type (DE-OS 35 40 660 A1), the valve needle has a ring-shaped shoulder stop in the area between a valve needle guide in the valve space and the clamping of the valve needle in the armature; this shoulder stop works in conjunction with a stop ring, which represents the stroke stop, in the valve chamber, the bore of which is less than the external diameter of the shoulder stop and which covers the valve space. The stop ring is positioned in the valve chamber in such a way that when the shoulder stop rests on the stop ring between the front faces of the magnet core and the armature, which face one another, a residual air gap remains. The needle valve return spring, formed as a cylindrical compression spring, is housed in the hollow cylindrical interior of the magnet core, and rests in a cavity at the front end of the armature. By screwing the setting tube into or out from the magnet core, the pretensioning of the return spring can be altered independently of the valve needle stroke, and thus the dynamic through-flow of the fuel injection valve can be set.
The ring-shaped stroke stop for the valve needle has the disadvantage that where the valve needle is not in precise alignment, the arresting face of the ring shoulder on the stop ring changes from ring-shaped to sickle-shaped; thus the valve needle stroke does not conform to the stroke set, and as a result the amount of fuel injected varies. In order to largely avoid this, the valve needle has two large-diameter guide sections, placed at a relatively large distance from one another, which slide along the interior wall of the valve space. In order to enable the axial through-flow of fuel, these guide sections are flattened on the side. These construction measures necessitate not only increased expenditure in manufacture, but also require a minimum length of the valve needle section to be in the valve space, so that it is not possible to go below a certain axial construction length of the fuel injection valve.